Storage system, storage control device, and storage control method

Abstract

A storage system includes: a first storage control device; and a second storage control device, wherein, when receiving a switching instruction to switch a device in charge that controls the I/O processing for the logical storage area from the first storage control device to the second storage control device, the first storage control device performs first switching processing of notifying the second storage control device of a management device number that indicates the first storage control device as a device that manages the cache, and executing response processing to switch the device in charge, and when receiving a determination request as to whether data requested to be read from the logical storage area by a readout request hits the cache, the first storage control device determines whether the data hits the cache, and the second storage control device transmits the determination request to the first storage control device.

What is claimed is: 
     
         1 . A storage system comprising:
 a first storage control device; and   a second storage control device, wherein,   in a state of controlling input/output (I/O) processing for a logical storage area using a cache, when receiving a switching instruction configured to switch a device in charge that controls the I/O processing for the logical storage area from the first storage control device to the second storage control device, the first storage control device performs first switching processing of notifying the second storage control device of a management device number that indicates the first storage control device as a device that manages the cache, and executing response processing for the switching instruction to switch the device in charge, and   when receiving a determination request as to whether data requested to be read from the logical storage area by a readout request hits the cache from the second storage control device after execution of the first switching processing, the first storage control device determines whether the data hits the cache, and   when receiving the readout request after execution of the first switching processing, the second storage control device transmits the determination request to the first storage control device indicated by the notified management device number.   
     
     
         2 . The storage system according to  claim 1 , wherein,
 in the first switching processing, the first storage control device stops the I/O processing for the logical storage area, and notifies the second storage control device of the management device number, executes the response processing, and causes the second storage control device to start the I/O processing for the logical storage area, and   moreover, when receiving the switching instruction,   the first storage control device stops the I/O processing for the logical storage area, copies management information configured to manage dirty data stored in the cache from a storage device in the first storage control device and transmits the copied management information to the second storage control device, and executes the response processing, and in a case of assuming that second switching processing of causing the second storage control device to start the I/O processing for the logical storage area is executed, the first storage control device calculates a stop time during which the I/O processing for the logical storage area stops on a basis of a data amount of the management information, and   the first storage control device executes the first switching processing in a case where the stop time exceeds a predetermined threshold value, or executes the second switching processing in a case where the stop time is equal to or less than the threshold value.   
     
     
         3 . The storage system according to  claim 2 , wherein,
 when receiving the readout request after execution of the second switching processing, the second storage control device determines whether the data hits the cache on a basis of the management information transmitted from the first storage control device.   
     
     
         4 . The storage system according to  claim 2 , wherein,
 after execution of the first switching processing, the first storage control device further sequentially writes back dirty data stored in the cache to a physical storage area that implements the logical storage area, and sequentially deletes information regarding the dirty data for which the write back has been completed from the management information, and   calculates the stop time on a basis of a current data amount of the management information during execution of the write back, and executes the second switching processing in a case where the calculated stop time becomes equal to or less than the threshold value.   
     
     
         5 . The storage system according to  claim 2 , wherein
 the first storage control device further sequentially writes back dirty data stored in the cache to a physical storage area that implements the logical storage area after execution of the second switching processing, and   starts use of a new cache secured in a storage area connected to the second storage control device in the I/O processing for the logical storage area by the second storage control device when the write back of all the dirty data in the cache has been completed.   
     
     
         6 . A storage control device comprising:
 a memory; and   a processor coupled to the memory and configured to:   in a state of controlling input/output (I/O) processing for a logical storage area using a cache, when receiving a switching instruction configured to switch a device in charge that controls the I/O processing for the logical storage area from the storage control device to another storage control device, perform first switching processing of notifying the another storage control device of a management device number that indicates the storage control device as a device that manages the cache, and executing response processing for the switching instruction to switch the device in charge; and   when receiving a determination request as to whether data requested to be read from the logical storage area by a readout request hits the cache from the another storage control device after execution of the first switching processing, determine whether the data hits the cache.   
     
     
         7 . The storage control device according to  claim 6 , wherein,
 in the first switching processing, the processor stops the I/O processing for the logical storage area, and notifies the another storage control device of the management device number, executes the response processing, and causes the second storage control device to start the I/O processing for the logical storage area, and   when receiving the switching instruction, the processor stops the I/O processing for the logical storage area, copies management information configured to manage dirty data stored in the cache from a storage device in the storage control device and transmits the copied management information to the another storage control device, and executes the response processing, and in a case of assuming that second switching processing of causing the another storage control device to start the I/O processing for the logical storage area is executed, the first storage control device calculates a stop time during which the I/O processing for the logical storage area stops on a basis of a data amount of the management information, and   the processor executes the first switching processing in a case where the stop time exceeds a predetermined threshold value, or executes the second switching processing in a case where the stop time is equal to or less than the threshold value.   
     
     
         8 . The storage control device according to  claim 7 , wherein,
 after execution of the first switching processing, the processor further sequentially writes back dirty data stored in the cache to a physical storage area that implements the logical storage area, and sequentially deletes information regarding the dirty data for which the write back has been completed from the management information, and   calculates the stop time on a basis of a current data amount of the management information during execution of the write back, and executes the second switching processing in a case where the calculated stop time becomes equal to or less than the threshold value.   
     
     
         9 . The storage control device according to  claim 7 , wherein
 the processor further sequentially writes back dirty data stored in the cache to a physical storage area that implements the logical storage area after execution of the second switching processing, and   starts use of a new cache secured in a storage area connected to the second storage control device in the I/O processing for the logical storage area by the another storage control device when the write back of all the dirty data in the cache has been completed.   
     
     
         10 . A storage control method comprising:
 in a state of controlling input/output (I/O) processing for a logical storage area using a cache, when receiving a switching instruction configured to switch a device in charge that controls the I/O processing for the logical storage area from the storage control device to another storage control device, performing, by a storage control device, first switching processing of notifying the another storage control device of a management device number that indicates the storage control device as a device that manages the cache, and executing response processing for the switching instruction to switch the device in charge; and   when receiving a determination request as to whether data requested to be read from the logical storage area by a readout request hits the cache from the another storage control device after execution of the first switching processing, determining whether the data hits the cache.